In many industrial fields, it is highly desirable to protect glass surface, metal surfaces and the surfaces of ceramic moldings from steam or rainwater, or from hydrophilic contaminants, in order to improve their durability, prevent corrosion and improve aesthetic appearance.
In particular, it is desirable to provide a water repellent treatment for automobile windshields which obviates the need to use wipers when driving at high speed, and a suitable material had therefore been long-awaited from the viewpoint of safe driving.
Many of the various water repellent agents already commercially available, however, require a thermal cure as an essential part of the treatment, and a curing catalyst had to be added when the agent was used. While these agents therefore do form a highly durable water repellent film, provided treatment conditions are ideal, they suffered from the drawback that they are very troublesome to use.
To resolve this problem, compositions containing alkylpolysiloxanes and acidic constituents as their active components are known as disclosed in Examined Japanese Patent Publication Nos. 50-15473 (U.S. Pat. No. 3,579,540) and 63-67828.
Although said compositions form a water repellent film which is relatively durable, it is necessary to add to them strong acids such as sulfuric acid, phosphoric acid, hydrochloric acid and fluorosulfonic acid. When they are applied to metal surfaces, therefore, they often create a corrosion problem, and even if the material being treated is not metal, there is a high risk of corroding adjacent metal parts.
As it was impossible to avoid the contact of said composition with workers' skin and clothing when coating them onto surfaces, an improvement was therefore desirable from the viewpoint of safety.